Maxim MAX44251AUA 20v, ultra-precision, low-noise op amp Datasheet

EVALUATION KIT AVAILABLE
MAX44250/MAX44251/MAX44252
20V, Ultra-Precision, Low-Noise Op Amps
General Description
The MAX44250/MAX44251/MAX44252 are 20V, ultraprecision, low-noise, low-drift amplifiers that offer nearzero DC offset and drift through the use of patented autocorrelating zeroing techniques. This method constantly
measures and compensates the input offset, eliminating
drift over time and temperature and the effect of 1/f noise.
These single, dual, and quad devices feature rail-to-rail
outputs, operate from a single 2.7V to 20V supply or dual
±1.35V to ±10V supplies and consume only 1.15mA
per channel, while providing 5.9nV/√Hz input-referred
voltage noise. The ICs are unity-gain stable with a gainbandwidth product of 10MHz.
With excellent specifications such as offset voltage of
6µV (max), drift of 19nV/°C (max), and 123nVP-P noise in
0.1Hz to 10Hz, the ICs are ideally suited for applications
requiring ultra-low noise and DC precision such as interfacing with pressure sensors, strain gauges, precision
weight scales, and medical instrumentation.
Benefits and Features
S 2.7V to 20V Power-Supply Range
S Integrated EMI Filter
S 6µV Input Offset Voltage (max) at Room
Temperature
S TCVOS of 19nV/°C (max)
S Low 5.9nV/√Hz Input-Referred Voltage Noise
S 123nVP-P in 0.1Hz to 10Hz
S Fast 400ns Settling Time
S 10MHz Gain-Bandwidth Product
S Rail-to-Rail Output
S High Accuracy Enables Precision Signal Chain
Acquisition
Applications
Strain Gauges
Pressure Transducers
Medical Instrumentation
Precision Instrumentation
Load Cell and Bridge Transducer Amplification
The ICs are available in 5-pin SOT23, 8-pin SOT23,
8-pin µMAXM, and 14-pin SO packages and are rated
over the -40°C to +125°C temperature range.
Ordering Information appears at end of data sheet.
For related parts and recommended products to use with this part,
refer to www.maximintegated.com/MAX44250.related.
Functional Diagrams appear at end of data sheet.
Typical Operating Circuit
3.3V
+10V
3V
MAX44251
R
BUFFER
R1
10V
-10V
RG
50RG
50RG
MAX44251
VDD
BUFFER
VDD
VREF
VIN+
R
MICROPROCESSOR
MAX11211OUTPUT
+10V
R
MAX44251
MAX6126
+10V
R
BUFFER
VOUT
-10V
1.5V
VIN-
VSS
C1
-10V
µMAX is a registered trademark of Maxim Integrated Products, Inc.
For pricing, delivery, and ordering information, please contact Maxim Direct
at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com.
19-6000; Rev 3; 4/13
MAX44250/MAX44251/MAX44252
20V, Ultra-Precision, Low-Noise Op Amps
Absolute Maximum Ratings
Supply Voltage (VDD to VSS).................................-0.3V to +22V
All Other Pins...................................(VSS - 0.3V) to (VDD + 0.3V)
Short-Circuit Duration to Either Supply Rail............................. 1s
Continuous Input Current (any pin).................................. ±20mA
Differential Input Voltage....................................................... ±6V
Maximum Power Dissipation (TA = +70°C)
5-Pin SOT23 (derate 3.1mW/°C above +70°C).........246.7mW
8-Pin SOT23 (derate 9.1mW/°C above +70°C)............727mW
µMAX (derate 4.5 mW/°C above +70°C).....................362mW
SO (derate 8.3 mW/°C above +70°C).......................666.7mW
Operating Temperature Range......................... -40°C to +125NC
Junction Temperature......................................................+150NC
Storage Temperature Range............................. -65°C to +150NC
Lead Temperature (soldering, 10s)............................... +300NC
Soldering Temperature (reflow)..................................... +260NC
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect device reliability.
Package Thermal Characteristics (Note 1)
5-Pin SOT23
Junction-to-Ambient Thermal Resistance (ΘJA)..... 324.3°C/W
Junction-to-Case Thermal Resistance (ΘJC)................82°C/W
8-Pin SOT23
Junction-to-Ambient Thermal Resistance (ΘJA)........ 196°C/W
Junction-to-Case Thermal Resistance (ΘJC)................70°C/W
µMAX
Junction-to-Ambient Thermal Resistance (ΘJA).........221°C/W
Junction-to-Case Thermal Resistance (ΘJC)................42°C/W
SO
Junction-to-Ambient Thermal Resistance (ΘJA).........120°C/W
Junction-to-Case Thermal Resistance (ΘJC)................37°C/W
Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer
board. For detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial.
Electrical Characteristics
(VDD = 10V, VSS = 0V, VIN+ = VIN- = VDD/2, RL = 10kI to VDD/2, TA = -40°C to +125°C, unless otherwise noted. Typical values are
at TA = +25°C.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
20
V
POWER SUPPLY
Supply Voltage Range
Power-Supply Rejection Ratio
(Note 3)
VDD
PSRR
Guaranteed by PSRR
2.7
VDD = 2.7V to 20V, VCM = 0V
140
Quiescent Current per Amplifier
(MAX44250)
IDD
RL = J
Quiescent Current per Amplifier
(MAX44251/MAX44252)
IDD
RL = J
Power-Up Time
tON
145
1.22
TA = +25NC
dB
1.7
1.85
-40NC < TA < +125NC
1.15
TA = +25NC
1.55
1.75
-40NC < TA < +125NC
25
mA
mA
Fs
DC SPECIFICATIONS
Input Common-Mode Range
Common-Mode Rejection Ratio
(Note 3)
Input Offset Voltage
(MAX44250) (Note 3)
Maxim Integrated
VCM
CMRR
VOS
Guaranteed by CMRR test
VSS 0.05
TA = +25NC, VCM = -0.05V to (VDD 1.5V)
133
-40NC < TA < +125NC
130
TA = +25NC
VDD 1.5
140
3
V
dB
9
FV
2
MAX44250/MAX44251/MAX44252
20V, Ultra-Precision, Low-Noise Op Amps
ELECTRICAL CHARACTERISTICS (continued)
(VDD = 10V, VSS = 0V, VIN+ = VIN- = VDD/2, RL = 10kI to VDD/2, TA = -40°C to +125°C, unless otherwise noted. Typical values are
at TA = +25°C.) (Note 2)
PARAMETER
Input Offset Voltage (MAX44251/
MAX44252)(Note 3)
SYMBOL
VOS
CONDITIONS
MIN
TA = +25NC
TYP
MAX
3
6
7
-40NC < TA < +125NC
UNITS
FV
Input Offset Voltage Drift
(MAX44250) (Note 3)
TC VOS
5
26
nV/NC
Input Offset Voltage Drift
(MAX44251/MAX44252)(Note 3)
TC VOS
5
19
nV/NC
Input Bias Current (MAX44250)
(Note 3)
IB
TA = +25NC
200
1400
pA
Input Bias Current (MAX44251/
MAX44252)(Note 3)
IB
TA = +25NC
200
1300
Input Offset Current (Note 3)
Open-Loop Gain (Note 3)
2400
-40NC < TA < +125NC
IOS
A­VOL
Output Short-Circuit Current
400
250mV P VOUT P
VDD - 250mV,
RL = 10kI to
VDD/2
To VDD or VSS
Output Voltage Low
(MAX44250)
VOL
VOUT - VSS
Output Voltage Low
(MAX44251/MAX44252)
VOL
VOUT - VSS
Output Voltage High
(MAX44250)
VOH
VDD - VOUT
Output Voltage High
(MAX44251/MAX44252)
VOH
VDD - VOUT
TA = +25NC
145
-40NC < TA <
+125NC
136
pA
pA
154
dB
Noncontinuous
96
mA
RL = 10kI to VDD/2
12
26
RL = 2kI to VDD/2
45
92
RL = 10kI to VDD/2
12
25
RL = 2kI to VDD/2
45
85
RL = 10kI to VDD/2
18
40
RL = 2kI to VDD/2
71
148
RL = 10kI to VDD/2
18
37
RL = 2kI to VDD/2
71
135
mV
mV
mV
mV
AC SPECIFICATIONS
Input Voltage-Noise Density
eN
Input Voltage Noise
Input Current-Noise Density
Input Capacitance
Gain-Bandwidth Product
iN
f = 1kHz
5.9
0.1Hz < f < 10Hz
123
nVP-P
f = 1kHz
0.6
pA/√Hz
CIN
2
pF
GBW
10
MHz
60
Degrees
8
V/Fs
500
pF
Phase Margin
PM
CL = 20pF
Slew Rate
SR
AV = 1V/V, VOUT = 2VP-P
Capacitive Loading
CL
No sustained oscillation, AV = 1V/V
VOUT = 2VP-P,
f = 1kHz
AV = +1V/V,
RL = 10kI to
f = 20kHz
VDD/2
To 0.01%, VOUT = 2V step, AV = -1V/V
Total Harmonic Distortion
Settling Time
Maxim Integrated
nV/√Hz
THD
-124
-119
400
dB
ns
3
MAX44250/MAX44251/MAX44252
20V, Ultra-Precision, Low-Noise Op Amps
ELECTRICAL CHARACTERISTICS
(VDD = 3.3V, VSS = 0V, VIN+ = VIN- = VDD/2, RL = 10kI to VDD/2, TA = -40°C to +125°C, unless otherwise noted. Typical values
are at TA = +25°C.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
1.17
1.65
UNITS
POWER SUPPLY
Quiescent Current Per Amplifier
(MAX44250)
IDD
RL = J
Quiescent Current Per Amplifier
(MAX44251/MAX44252))
IDD
RL = J
Power-Up Time
tON
TA = +25NC
-40NC < TA < +125NC
1.80
TA = +25NC
1.1
-40NC < TA < +125NC
1.5
1.65
25
mA
mA
Fs
DC SPECIFICATIONS
Input Common-Mode Range
Common-Mode Rejection Ratio
(Note 3)
VCM
CMRR
Input Offset Voltage
(MAX44250)(Note 3)
VOS
Input Offset Voltage (MAX44251/
MAX44252)(Note 3)
VOS
Guaranteed by CMRR test
VSS 0.05
TA = +25NC, VCM = -0.05V to (VDD 1.5V)
120
-40NC < TA < +125NC
117
TA = +25NC
VDD 1.5
129
dB
3
8.5
3
5.5
-40NC < TA < +125NC
V
6.5
FV
FV
Input Offset Voltage Drift
(MAX44250)(Note 3)
TC VOS
8
25
nV/NC
Input Offset Voltage Drift
(MAX44251/MAX44252)(Note 3)
TC VOS
8
18
nV/NC
Input Bias Current
(MAX44250)(Note 3)
IB
200
1450
pA
Input Bias Current (MAX44251/
MAX44252)(Note 3)
IB
200
1100
Input Offset Current (Note 3)
IOS
Open-Loop Gain (Note 3)
AVOL
Output Short-Circuit Current
TA = +25NC
-40NC < TA < +125NC
400
250mV P VOUT
P VDD - 250mV,
RL = 10kI to
VDD/2
TA = +25NC
136
-40NC < TA < +125NC
133
To VDD or VSS
Noncontinuous
Output Voltage Low
(MAX44250)
VOL
VOUT - VSS
Output Voltage Low
(MAX44251/MAX44252)
VOL
VOUT - VSS
Output Voltage High
VOH
VDD - VOUT
Maxim Integrated
1200
pA
pA
151
dB
58
mA
RL = 10kI to VDD/2
5
26
RL = 2kI to VDD/2
17
46
RL = 10kI to VDD/2
5
22
RL = 2kI to VDD/2
17
42
RL = 10kI to VDD/2
9
22
RL = 2kI to VDD/2
29
52
mV
mV
mV
4
MAX44250/MAX44251/MAX44252
20V, Ultra-Precision, Low-Noise Op Amps
ELECTRICAL CHARACTERISTICS (continued)
(VDD = 3.3V, VSS = 0V, VIN+ = VIN- = VDD/2, RL = 10kI to VDD/2, TA = -40°C to +125°C, unless otherwise noted. Typical values are
at TA = +25°C.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
AC SPECIFICATIONS
Input Voltage-Noise Density
eN
Input Voltage Noise
Input Current-Noise Density
Input Capacitance
Gain-Bandwidth Product
iN
f = 1kHz
6.2
nV/√Hz
0.1Hz < f < 10Hz
123
nVP-P
f = 1kHz
0.3
pA/√Hz
CIN
2
pF
GBW
10
MHz
Phase Margin
PM
CL = 20pF
60
Degrees
Slew Rate
SR
AV = 1V/V, VOUT = 1VP-P, 10% to 90%
5
V/Fs
Capacitive Loading
CL
No sustained oscillation, AV = 1V/V
500
pF
Total Harmonic Distortion
VOUT = 1VP-P,
AV = +1V/V,
VCM = VDD/4,
RL = 10kI to
VDD/2
THD
f = 1kHz
-124
dB
f = 20kHz
-100
To 0.01%, VOUT = 1V step, AV = -1V/V
Settling Time
200
ns
Note 2: All devices are 100% production tested at TA = +25°C. Temperature limits are guaranteed by design.
Note 3: Guaranteed by design.
Typical Operating Characteristics
(VDD = 10V, VSS = 0V, outputs have RL = 10kI to VDD/2. TA = +25NC, unless otherwise specified.)
INPUT OFFSET VOLTAGE DRIFT HISTOGRAM
SUPPLY CURRENT (mA)
35
30
25
20
15
10
Maxim Integrated
TA = +85°C
1.0
TA = +25°C
TA = 0°C
TA = -40°C
0.8
0.6
0.4
SUPPLY CURRENT
PER AMPLIFIER
0.2
0
OFFSET VOLTAGE (µV)
TA = +125°C
1.2
MAX44250 toc03
40
5
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
SUPPLY CURRENT vs. SUPPLY VOLTAGE
1.4
MAX44250 toc02
45
PERCENT OCCURRENCE (%)
MAX44250 toc01
PERCENT OCCURRENCE (%)
OFFSET VOLTAGE HISTOGRAM
75
70
65
60
55
50
45
40
35
30
25
20
15
10
5
0
0
-0.001 0
0.001 0.002 0.003 0.004 0.005 0.006
OFFSET VOLTAGE DRIFT (µV/°C)
0
5
10
15
20
25
SUPPLY VOLTAGE (V)
5
MAX44250/MAX44251/MAX44252
20V, Ultra-Precision, Low-Noise Op Amps
Typical Operating Characteristics (continued)
(VDD = 10V, VSS = 0V, outputs have RL = 10kI to VDD/2. TA = +25NC, unless otherwise specified.)
INPUT OFFSET VOLTAGE
vs. INPUT COMMON MODE
1.24
5
1.22
5
VOS (µV)
1.18
1.16
1.14
1.12
SUPPLY CURRENT
PER AMPLIFIER
1.08
4
VOS (µV)
4
1.20
1.10
3
2
1
1
-25
0
25
50
75
100 125 150
2
4
6
8
10
-25
0
25
50
75
100
INPUT COMMON VOLTAGE (V)
TEMPERATURE (°C)
INPUT BIAS CURRENT
vs. COMMON-MODE VOLTAGE
INPUT BIAS CURRENT
vs. TEMPERATURE
COMMON-MODE REJECTION RATIO
vs. FREQUENCY
TA = +25°C
500
0
-500
-250
-1500
0
-20
-1250
-2
-1
0
1
2
3
INPUT COMMON-MODE VOLTAGE (V)
Maxim Integrated
4
60
20
-1000
IBIAS+
80
40
NEGATIVE IBIAS
-750
-1000
-3
120
100
0
-500
-4
140
250
IBIAS (pA)
1000
POSITIVE IBIAS
500
160
CMRR (dB)
TA = -40°C
750
125
MAX44250 toc09
1000
MAX44250 toc07
TA = +125°C
IBIAS-
-5
-50
TEMPERATURE (°C)
2000
1500
0
0
MAX44250 toc08
-50
3
2
0
1.06
INPUT BIAS CURRENT (pA)
6
MAX44250 toc05
1.26
SUPPLY CURRENT (mA)
6
MAX44250 toc04
1.28
INPUT OFFSET VOLTAGE
vs. TEMPERATURE
MAX44250 toc06
SUPPLY CURRENT vs. TEMPERATURE
-50
-25
0
25
50
75
TEMPERATURE (°C)
100 125 150
0.1
1
10 100 1k 10k 100k 1M 10M 100M
FREQUENCY (Hz)
6
MAX44250/MAX44251/MAX44252
20V, Ultra-Precision, Low-Noise Op Amps
Typical Operating Characteristics (continued)
(VDD = 10V, VSS = 0V, outputs have RL = 10kI to VDD/2. TA = +25NC, unless otherwise specified.)
400
300
200
250
25
200
150
100
20
15
10
100
50
5
0
0
0
6
8
10
0
2
OUTPUT VOLTAGE SWING LOW
vs. TEMPERATURE
12
10
8
6
4
2
-50
10
140
120
0
25
50
75
100
80
60
40
20
0
1
15
10
5
INPUT CURRENT NOISE vs. FREQUENCY
MAX44250 toc17
5
4
0
-2
MAGNITUDE (dB)
INPUT CURRENT NOISE (pA/√Hz)
2
10k
100k
3
2
-4
-6
-8
-10
-12
-14
1
VIN = 100mVP-P
-16
-18
1
10
100
FREQUENCY (Hz)
Maxim Integrated
1k
SMALL-SIGNAL RESPONSE
0
1s /div
100
10
FREQUENCY (Hz)
6
0.2µV/div
100 125 150
20
FREQUENCY (Hz)
MAX44250 toc16
75
25
10 100 1k 10k 100k 1M 10M 100M
TEMPERATURE (°C)
INPUT VOLTAGE 0.1Hz TO 10Hz NOISE
50
0
0.1
100 125 150
25
30
-60
0
-25
0
INPUT VOLTAGE NOISE vs. FREQUENCY
-20
-40
RL = 10kI to VDD/2
-50
-25
TEMPERATURE (°C)
OPEN-LOOP GAIN vs. FREQUENCY
OPEN-LOOP GAIN (dB)
14
8
MAX44250 toc14
16
6
180
160
MAX44250 toc13
18
4
OUTPUT SINK CURRENT (mA)
MAX44250 toc15
4
RL = 10kI to VDD/2
MAX44250 toc18
2
OUTPUT SOURCE CURRENT (mA)
INPUT VOLTAGE NOISE (nV/√Hz)
0
VOL (mV)
30
VOH (mV)
OUTPUT VOLTAGE LOW (mV)
500
35
MAX44250 toc11
300
MAX44250 toc10
OUTPUT VOLTAGE HIGH (mV)
600
OUTPUT VOLTAGE SWING HIGH
vs. TEMPERATURE
OUTPUT VOLTAGE LOW
vs. OUTPUT SINK CURRENT
MAX44250 toc12
OUTPUT VOLTAGE HIGH
vs. OUTPUT SOURCE CURRENT (VDD - VOH)
1k
10k
1
10
100
1k
10k 100k 1M 10M 100M
FREQUENCY (Hz)
7
MAX44250/MAX44251/MAX44252
20V, Ultra-Precision, Low-Noise Op Amps
Typical Operating Characteristics (continued)
(VDD = 10V, VSS = 0V, outputs have RL = 10kI to VDD/2. TA = +25NC, unless otherwise specified.)
SMALL-SIGNAL STEP RESPONSE
vs. TIME
LARGE-SIGNAL RESPONSE
MAX44250 toc20
MAX44250 toc19
0
-5
MAX44250 toc21
AV = 1V/V
VIN = 100mVP-P
VOLTAGE (100mV/div)
-10
-15
-20
-25
-30
-35
AV = 1V/V
VIN = 2VP-P
INPUT
INPUT
VOLTAGE (1V/div)
5
MAGNITUDE (dB)
LARGE-SIGNAL STEP RESPONSE
vs. TIME
OUTPUT
OUTPUT
-40
VIN = 2VP-P
-45
-50
0.1
1
10 100 1k 10k 100k 1M 10M 100M
TIME (2µs/div)
TIME (2µs/div)
TOTAL HARMONIC DISTORTION
vs. FREQUENCY
TOTAL HARMONIC DISTORTION
vs. INPUT VOLTAGE
FREQUENCY (Hz)
-105
-110
MAGNITUDE (dB)
VOLTAGE (1V/div)
VSS = 5V
-115
-120
-125
VOFFSET
(10mV/div)
100
10k
TIME (10µs/div)
STABILITY vs. CAPACITIVE AND
RESISTIVE LOAD IN PARALLEL WITH CL
STABILITY vs. CAPACITIVE AND
RISO IN SERIES WITH CLOAD
7
UNSTABLE
40
5
4
UNSTABLE
2
20
100
1k
CAPACITIVE LOAD (pF)
Maxim Integrated
10k
1.25
1.50
1.75
2.00
80
70
60
50
40
30
10
0
0
0
1.00
20
1
10
0.75
MAX44251 EMIRR
3
30
0.50
INPUT VOLTAGE (V)
EMIRR (dB)
STABLE
50
RISO (I)
60
STABLE
6
70
0.25
100k
MAX44250 toc26
8
MAX44250 toc25
80
RESISTIVE LOAD (kI)
1k
FREQUENCY (Hz)
90
-80
-140
-140
100
-60
-120
-135
25µs
-40
-100
-130
0V
VCC = 3.3V
-20
MAGNITUDE (dB)
VDD = VSS = 0V
0
MAX44250 toc23
-100
VDD = 5V
MAX44250 toc27
MAX44250 toc22
SUPPLY
VOLTAGE
(5V/div)
0V
MAX44250 toc24
POWER-UP TIME
100
1k
10k
CAPACITIVE LOAD (pF)
100k
10
100
1000
10,000
FREQUENCY (MHz)
8
MAX44250/MAX44251/MAX44252
20V, Ultra-Precision, Low-Noise Op Amps
Pin Configurations
TOP VIEW
+
OUTA
1
5
VDD
MAX44250
VSS 2
INA+ 3
4
N.C.
1
INAINA+
2
3
VSS
4
+
8
MAX44250
N.C.
7
VDD
6
OUTA
5
N.C.
INA-
8 µMAX
5 SOT23
OUTA 1
+
OUTA
1
8 VDD
INA-
2
7 OUTB
INA+
3
6 INB-
VSS
4
5 INB+
MAX44251
+
INA- 2
OUTA
1
INA-
2
INA+
3
VSS
4
+
8
MAX44251
VDD
7
OUTB
6
INB-
5
INB+
8 µMAX
8 SOT23
14 OUTD
MAX44252
13 IND-
INA+ 3
12 IND+
VDD 4
11 VSS
INB+ 5
10 INC+
INB- 6
9 INC-
OUTB 7
8 OUTC
14 SO
Pin Description
PIN
MAX44250
MAX44251
MAX44252
NAME
FUNCTION
5 SOT23
8 µMAX
8 SOT23
8 µMAX
14 SO
1
6
1
1
1
OUTA
4
2
2
2
2
INA-
Channel A Negative Input
3
3
3
3
3
INA+
Channel A Positive Input
2
4
4
4
11
VSS
Negative Supply Voltage
Channel A Output
—
—
5
5
5
INB+
Channel B Positive Input
—
—
6
6
6
INB-
Channel B Negative Input
—
—
7
7
7
OUTB
5
7
8
8
4
VDD
Channel B Output
Positive Supply Voltage
—
—
—
—
8
OUTC
—
—
—
—
9
INC-
Channel C Negative Input
—
—
—
—
10
INC+
Channel C Positive Input
Channel D Positive Input
—
—
—
—
12
IND+
—
—
—
—
13
IND-
—
—
—
—
14
OUTD
—
1, 5, 8
—
—
—
N.C.
Maxim Integrated
Channel C Output
Channel D Negative Input
Channel D Output
No Connection
9
MAX44250/MAX44251/MAX44252
20V, Ultra-Precision, Low-Noise Op Amps
Detailed Description
The MAX44250/MAX44251/MAX44252 are high-precision amplifiers that have less than 3FV of typical inputreferred offset and low flicker noise. These characteristics are achieved through an autozeroing technique that
samples and finds repeating patterns of signal to cancel
the input offset voltage and 1/f noise of the amplifier.
Autozero
The ICs feature an autozero circuit that allows the devices
to achieve less than 6FV (max) of input offset voltage at
room temperature and eliminate the 1/f noise.
Electromagnetic interference (EMI) noise occurs at higher frequency that results in malfunction or degradation of
electrical equipment.
The ICs have an input EMI filter to avoid the output getting affected by radio frequency interference. The EMI
filter composed of passive devices presents significant
higher impedance to higher frequency.
High Supply Voltage Range
The ICs feature 1.15mA current consumption per channel
and a voltage supply range from either 2.7V to 20V single
supply or ±1.35V to ±10V split supply.
Applications Information
Noise Suppression
Flicker noise, inherent in all active devices, is inversely
proportional to frequency presented. Charges at the
oxide-silicon interface that are trapped-and-released by
MOSFET oxide occurs at low frequency more often. For
this reason, flicker noise is also called 1/f noise.
The ICs are ultra-high-precision operational amplifiers with
a high supply voltage range designed for load cell, medical instrumentation and precision instrument applications.
These devices are also designed to interface with pressure transducers and are ideal for precision weight scale
application as shown in Figure 1.
3.3V
+10V
MAX44251
3V
BUFFER
R
R1
10V
-10V
RG
50RG
MAX44251 BUFFER
VDD
BUFFER
VDD
VREF
VIN+
R
+10V
MAX6126
+10V
R
50RG
VOUT
MICROPROCESSOR
MAX11211OUTPUT
R
1.5V
-10V
VIN-
VSS
C1
MAX44251
-10V
Figure 1. Weight Scale Application Circuit
Maxim Integrated
10
MAX44250/MAX44251/MAX44252
20V, Ultra-Precision, Low-Noise Op Amps
ADC Buffer Amplifier
The MAX44250/MAX44251/MAX44252's low input offset
voltage, low noise, and fast settling time make these
amplifiers ideal for ADC buffers. Weigh scales are one
application that often require a low-noise, high-voltage
amplifier in front of an ADC. Figure 1 details an example
of a load cell and amplifier driven from the same Q10V
supplies, along with the MAX11211 18-bit delta sigma
ADC. Load cells produce a very small voltage change at
their outputs, therefore driving the excitation source with
a higher voltage produces a wider dynamic range that
can be measured at the ADC inputs.
The MAX11211 ADC operates from a single 2.7V to 3.6V
analog supply, offers 18-bit noise-free resolution and
0.86mW power dissipation. The MAX11211 also offers
> 100dB rejection at 50Hz and 60Hz. This ADC is part of
a family of 16-, 18-, 20-, and 24-bit delta sigma ADCs with
high precision and < 1mW power dissipation.
The MAX44250/MAX44251/MAX44252's low input offset
voltage and low noise allow a gain circuit prior to the
MAX11211 without losing any dynamic range at the ADC.
The ICs, with a typical offset drift of 5nV/°C, guarantee
that the drift over a 10°C range is only 50nV. Setting this
equal to 0.5 LSB in a 18-bit system yields a full-scale
range of 13mV. With a single 10V supply, an acceptable
closed-loop gain of 770V/V provides sufficient gain while
maintaining headroom.
Precision Low-Side Current Sensing
The ICs’ autozero feature produces ultra-low offset
voltage and drift, making them ideal for precision current-sensing applications. Figure 2 shows the ICs in
a low-side current-sense configuration. This circuit produces an accurate output voltage, VOUT equal to ILOAD
x RSENSE x (1 + R2/R1).
R2
VSUPPLY
R1
ILOAD
Error Budget Example
When using the ICs as an ADC buffer in strain gauge
application, the temperature drift should be taken into
consideration to determine maximum input signal. A
typical strain gauge has sensitivity specification of just
2mV/V at rated out load. This means that when the strain
gauge load cell is powered with 10V, the full-scale output
voltage is 20mV. In this application, both offset voltage
and drift are critical parameters that directly affect the
accuracy of measurement. Even though offset voltage
could be calibrated out, its drift over temperature is still
a problem.
Maxim Integrated
OUT
MAX44251
MAX44252
RSENSE
Figure 2. Low-Side Current Sensing
11
MAX44250/MAX44251/MAX44252
20V, Ultra-Precision, Low-Noise Op Amps
Functional Diagrams
TOP VIEW
+
+
OUT 1
5
OUTA 1
VDD
VSS 2
IN+ 3
4
IN-
8
VDD
INA- 2
7
OUTB
INA+
3
6
INB-
VSS 4
5
INB+
MAX44251
MAX44250
+
OUTA
+
1
14 OUTD
8
N.C.
INA- 2
13 IND-
IN- 2
7
VDD
INA+
3
12 IND+
IN+
3
6
OUT
VDD 4
VSS 4
5
N.C.
INB+ 5
10 INC+
INB- 6
9
INC-
OUTB 7
8
OUTC
N.C. 1
MAX44250
Chip Information
MAX44252
11 VSS
Ordering Information
PROCESS: BiCMOS
TEMP RANGE
PINPACKAGE
TOP
MARK
MAX44250AUK+
-40NC to +125NC
5 SOT23
AFMA
MAX44250AUA+
-40NC to +125NC
8 FMAX
—
MAX44251AKA+
-40NC to +125NC
8 SOT23
AERC
MAX44251AUA+
-40NC to +125NC
8 FMAX
—
MAX44252ASD+
-40NC to +125NC
14 SO
—
PART
+Denotes a lead(Pb)-free/RoHS-compliant package.
Maxim Integrated
12
MAX44250/MAX44251/MAX44252
20V, Ultra-Precision, Low-Noise Op Amps
Package Information
For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a “+”,
“#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing
pertains to the package regardless of RoHS status.
PACKAGE TYPE
PACKAGE CODE
OUTLINE NO.
LAND PATTERN
5 SOT23
U5+1
21-0057
90-0174
8 SOT23
K8+5
21-0078
90-0176
8 FMAX
U8+1
21-0036
90-0092
14 SO
S14M+5
21-0041
90-0096
Maxim Integrated
13
MAX44250/MAX44251/MAX44252
20V, Ultra-Precision, Low-Noise Op Amps
Revision History
REVISION
NUMBER
REVISION
DATE
0
10/11
Initial release
1
12/11
Released the MAX44252 and updated the Typical Operating Characteristics.
2
8/12
Added the MAX44250 to the data sheet, added MAX44251 EMIRR graph to Typical
Operating Characteristics, and revised Figure 2.
1–16
3
4/13
Updated General Description, Typical Operating Circuit, and Figure 1.
1, 10
DESCRIPTION
PAGES
CHANGED
—
5, 6, 11
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent
licenses are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and
max limits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
Maxim Integrated 160 Rio Robles, San Jose, CA 95134 USA 1-408-601-1000
©
2013 Maxim Integrated
14
The Maxim logo and Maxim Integrated are trademarks of Maxim Integrated Products, Inc.
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